Halogenated thiophene monomer for the preparation of regioregular polythiophenes

ABSTRACT

Conductive polymers and a method of forming conductive polymers. More particularly, a method of forming head-to-tail coupled regioregular poly-(3-substituted) thiophenes having improved charge carrier mobility and current modulation. Also, monomers having two different halogen leaving groups and which form regioregular poly-(3-substituted) thiophenes more efficiently and economically than other processes. Polythiophene polymers, films and articles are also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of forming conductive polymers. Moreparticularly, the invention pertains to a method of forming head-to-tailcoupled regioregular (rr) poly-(3-substituted) thiophenes. The inventionalso provides monomers suitable for the formation of regioregularpoly-(3-substituted) thiophenes, regioregular substitutedpolythiophenes, as well as films and articles formed therefrom.

2. Description of the Related Art

As is well known, various materials can conduct electricity in differentways. For instance, metals conduct electricity by the movement of freeelectrons that are not tightly bound to any single atom. Insemiconductors, like those that make up transistors and other electronicdevices, electricity is produced by the drift of excess electrons thatform a negative current, or alternatively the drift of missing electronsor positive “holes” in the opposite direction to form a positivecurrent. Typically, these excess electrons or holes are donated byimpurities or dopant atoms.

In the 1970s, it was discovered that polymers can be made to conductelectricity like metallic conductors and semiconductors. At the time,plastics were considered non-conductors, but it was discovered thatadding impurities to a polymer material could increase its conductivityby more than a billion times. Today, the field of conducting polymershas been greatly expanded to a broad field of commercial applications.

Conducting polymers are finding increased use compared to otherconductive materials because they are lightweight, highly processableand have good mechanical properties. Potential applications forconducting polymers include field-effect transistors, sensors, capacitorcoatings, battery electrodes, light-emitting diodes, nonlinear opticalmaterials, molecular wires and molecular switches. Among polymers thathave shown conductive properties, polythiophenes are particularlydesirable because of their excellent conductivity and processability. Ofparticular interest in the art are poly(3-alkylthiophenes) (P3ATs),including poly(3-hexylthiophene) (P3HT), which are attractive conductivepolymer materials for many potential commercial applications because thealkyl side chains offer improved solubility in many common organicsolvents, particularly ethers. Today, poly(3-alkylthiophenes) are widelyused as hole-transporting materials in organic field-effect transistors.

To those skilled in the art of conductive polythiophene polymers, it iswell known that the degree of conductivity exhibited by conductivepolymers depends on their degree of order on a molecular level. This isdue in part to a crystal lattice structure that allows an overlappingpathway for electrons. To illustrate, the conductivity ofpoly-(3-substituted thiophenes) is known to increase with the degree ofregioregularity. Because of its asymmetrical structure, thepolymerization of 3-substituted thiophene produces a mixture ofpolythiophene structures containing three possible regiochemicallinkages between repeat units depending on the specific synthesisprocedure. The three orientations available when two thiophene rings arejoined are the 2,2′, 2,5′, and 5,5′ couplings. When application as aconducting polymer is desired, the 2,2′ (or head-to-head) coupling andthe 5,5′ (or tail-to-tail) coupling, referred to as regiorandomcouplings, are considered to be defects in the polymer structure becausethey cause a sterically driven twist of thiophene rings that disruptconjugation, produce an amorphous structure, and prevent ideal solidstate packing, thus diminishing electronic and photonic properties. Thesteric crowding of solubilizing groups in the 3 position leads to lossof planarity and less π overlap. In contrast, the 2,5′ (or head-to-tail(HT) coupled) regioregular polythiophenes can access a low energy planarconformation, leading to highly conjugated polymers that provide flat,stacking macromolecular structures that can self-assemble, providingefficient interchain and intrachain conductivity pathways. Theelectronic and photonic properties of the regioregular materials aremaximized.

Various methods have been employed to synthesize 2,5′ regioregularpolythiophenes. Two of the more commonly known methods are the“McCullough method”, described in U.S. Pat. No. 6,166,172 by Richard D.McCullough and Robert S. Loewe of Carnegie Mellon University, and the“Rieke method”, described in U.S. Pat. No. 5,358,546 by Reuben D. Riekeof the University of Nebraska. The McCullough method region-specificallygenerates 2-bromo-5-(bromomagnesio)-3-alkylthiophene from a monomerwhich is polymerized with catalytic amounts of1,3-diphenylphosphinopropane nickel(II) chloride (Ni(dppp)Cl₂) usingKumada cross-coupling methods. The Rieke method differs from theMcCullough method primarily in the synthesis of an asymmetricorganometallic intermediate. Rieke describes adding a2,5-dibromo-3-alkylthiophene to a solution of highly reactive “Riekezinc” to form a mixture of the isomers, 2-bromo-3-alkyl-5-(bromozincio)thiophene and 2-(bromozincio)-3-alkyl-5-bromothiophene. The addition of1,2-bis(diphenylphosphino)ethane nickel(II) chloride (Ni(dppe)Cl₂), anickel cross-coupling catalyst, leads to the formation of regioregularHT-poly(3-alkylthiophenes). Each of these methods produce polythiopheneswith a high percentage of HT couplings, in the range of 90% or higher. Adetailed description of both the McCullough method and the Rieke method,as well as other methods, are illustrated in detail in U.S. Pat. No.6,166,172.

Despite the efforts by those skilled in the art to improve HT couplingtechniques, the synthetic procedures heretofore described havesignificant drawbacks. For example, the McCullough method requireshighly purified starting materials, the most important of which is themonomer, 2-bromo-3-alkylthiophene. The need for purity adds to the costof the synthesis. The Rieke method includes an easily purified2,5-dibromo-3-alkylthiophene as a starting material, but requires thedifficult preparation of Rieke zinc via alkali metal reduction of zinchalides in an inert environment. Accordingly, a new method for thepreparation of regioregular, HT-poly-(3-alkylthiophenes) is needed thatis efficient and economical. It has been unexpectedly found thatpoly(3-substituted) thiophenes formed with a thiophene monomer havingtwo different halogen leaving groups will result in a thiophene polymerhaving superior conductive properties and at a higher yield and lowercost than other known processes. Additionally,poly(3-substituted)thiophenes of the invention have been found to haveimproved charge carrier mobility and current modulation (on/off ratio)properties compared to polythiophenes formed via prior art processes.

SUMMARY OF THE INVENTION

The invention provides a method of forming a substituted polythiophene,comprising:a) providing a solvent soluble, substituted thiophene monomer, whereinsaid monomer has the structure:

wherein X₁ and X₂ are different and each comprises a halogen atom, withat least one of the halogen atoms being capable of bonding withmagnesium; R₁ comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀aryl group, fluorine or NO₂; R₂ comprises hydrogen, fluorine, NO₂ or aC₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group, a C₁ to C₂₀ O-alkylgroup, a C₁ to C₂₀ S-alkyl group or a C₆ to C₂₀ aryl group;b) combining the substituted thiophene monomer with magnesium and asolvent to form a regiochemical intermediate; andc) reacting the regiochemical intermediate with a polymerizationcatalyst under conditions sufficient to polymerize the intermediateproducing a regioregular, substituted polythiophene reaction producthaving repeating units of the structure:

wherein R comprises either a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ toC₂₀ aryl group, fluorine or NO₂; the polymer having a charge carriermobility (μ) of at least about 1×10⁻² cm²/Vs and an on/off ratio of atleast about 1×10³, and wherein n comprises from about 2 to about 10,000.

The invention also provides a compound having the structure:

or,

wherein R comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group,a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀ arylgroup, fluorine or NO₂, and wherein n comprises from about 2 to about10,000.

The invention further provides a regioregular polythiophene polymerhaving repeating units of the structure:

wherein R comprises either a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ toC₂₀ aryl group, fluorine or NO₂; the polymer having a charge carriermobility (μ) of at least about 1×10⁻² cm²/Vs and an on/off ratio of atleast about 1×10³, and wherein n comprises from about 2 to about 10,000.

The invention still further provides a film formed from a regioregular,substituted polythiophene, which film is formed by:

I. forming a regioregular, substituted polythiophene by:

-   -   a) providing a solvent soluble, substituted thiophene monomer,        wherein said monomer has the structure:    -   wherein X₁ and X₂ are different and each comprises a halogen        atom, with at least one of the halogen atoms being capable of        bonding with magnesium; R₁ comprises a C₁ to C₂₀ alkyl group, a        C₁ to C₂₀ F-alkyl group, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀        S-alkyl group or a C₆ to C₂₀ aryl group, fluorine or NO₂; R₂        comprises hydrogen, fluorine, NO₂ or a C₁ to C₂₀ alkyl group, a        C₁ to C₂₀ F-alkyl group, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀        S-alkyl group or a C₆ to C₂₀ aryl group;    -   b) combining the substituted thiophene monomer with magnesium        and a solvent to form a regiochemical intermediate; and    -   c) reacting the regiochemical intermediate with a polymerization        catalyst under conditions sufficient to polymerize the        intermediate producing a substituted polythiophene reaction        product; the polythiophene having a regioregularity of at least        about 90%, a charge carrier mobility (μ) of at least about        1×10⁻² cm²/Vs and an on/off ratio of at least about 1×10³; and        II. forming the regioregular, substituted polythiophene of (I)        into a film.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a method for producing regioregularpoly(3-substituted) thiophenes from a solvent soluble, substitutedthiophene monomer, wherein said monomer has the structure:

wherein X₁ and X₂ are different and each comprises a halogen atom, withat least one of the halogen atoms being capable of bonding withmagnesium; R₁ comprises an alkyl group having at least one carbon atom,and preferably comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ fluorinesubstituted alkyl group (F-alkyl group), a C₁ to C₂₀ oxygen substitutedalkyl group (O-alkyl group), a C₁ to C₂₀ sulfur substituted alkyl group(S-alkyl group), a C₆ to C₂₀ aryl group, fluorine or NO₂; R₂ compriseshydrogen, fluorine, NO₂ or a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ O-alkylgroup, a C₁ to C₂₀ S-alkyl group, a C₁ to C₂₀ F-alkyl group or a C₆ toC₂₀ aryl group. R₁ may also comprise hydrogen, but R₁ and R₂ may notcomprise hydrogen at the same time. This substituted thiophene monomeris combined with magnesium metal and a solvent, e.g. an ether, to form aregiochemical intermediate. This regiochemical intermediate is reactedwith a polymerization catalyst under conditions sufficient to polymerizethe intermediate, producing a regioregular substituted polythiophenereaction product. In the preferred embodiment of the invention, the R₁group comprises a C₁ to C₂₀ alkyl group. An alkyl group is preferredbecause they are known to improve the solubility of the thiophene inorganic solvents. More preferred are either a hexyl (C₆) or decyl (C₁₀)group. Most preferably, the R₁ group comprises a hexyl group, becausesuperior mobility properties have been found for regioregularpolythiophenes substituted with linear hexyl side chains. The R₁ groupmust comprise a group that is non-reactive with the organomagnesiumGrignard reagent or otherwise must be protected from reacting witheither the Grignard reagent or polymerization catalyst, as is well knownin the art. In the preferred embodiment of the invention the R₂ groupcomprises hydrogen. Importantly, if the R₂ group is substituted, such aswith an alkyl group, then R₁ must be hydrogen in order to have aregioregular polythiophene. Thus, if the R₁ group is substituted then R₂must be hydrogen in order to have a regioregular polythiophene Also, X₁and X₂ preferably bromine and chlorine, or vice-versa, although otherhalogens, such as iodine, are also acceptable. It is also within thescope of the invention for either R₁ or R₂ to comprise an alkyl, aryl orsubstituted-alkyl group having greater than C₂₀ (e.g. C₅₀ or above).

Particularly superior results have been achieved using a startingthiophene monomer wherein R₁ is a hexyl group, R₂ is hydrogen, and X₁and X₂ are either chlorine or bromine. Accordingly, regioregularpoly(substituted) thiophenes having excellent properties have beenproduced wherein the starting thiophene monomer comprises either2-bromo-5-chloro-hexylthiophene or 5-bromo-2-chloro-hexylthiophene, or2-bromo-5-chloro-4-hexylthiophene or 5-bromo-2-chloro-4-hexylthiophene.

The soluble thiophene monomer is combined with magnesium metal at amonomer:magnesium ratio of about 0.8:1.2, more preferably about 0.9:1.1and most preferably in an equimolar 1:1 ratio. The two are combined inthe presence of an organic solvent. The preferred solvent is anon-reactive dry (anhydrous) ether, ethylether, diethylether or drytetrahydrofuran (THF) solvent. Non-reactive, anhydrous or “dry” solventsare typically necessary because Grignard reagents are highly reactivewith water. In a more preferred embodiment, the solvent is drymethyl-THF, e.g. 2-methyl-THF. 2-Methyl-THF is preferred because it hasbeen found as the most successful solvent for reducing or eliminatingthe formation of interfering reaction side-products, and allows for theuse of higher concentrations of both the Grignard reagent and thecatalyst. In the preferred embodiment of the invention, the thiophenemonomer is present in a concentration in the solvent of about 0.1 mol/Lto about 2 mol/L, more preferably about 0.25 mol/L to 1 mol/L, and mostpreferably about 0.5 mol/L to 0.7 mol/L.

To assist in the initiation of a reaction between the magnesium metaland the thiophene monomer, a catalytic amount of the organomagnesiumGrignard reagent is preferably added to the reaction mixture. For thepurposes of the invention, a catalytic amount comprises from about 0.1to about 20.0 mol % of the Grignard reagent, more preferably from about0.1 to about 10.0 mol % and most preferably from about 1 to about 5 mol%. The organomagnesium Grignard reagent (R′MgX′) may generally be anyalkylmagnesiumhalide or arylmagnesiumhalide Grignard reagent as is knownby those skilled in the art. X′ may be any halogen, but is typically Br,Cl or I, and R′ may comprise an alkyl group having at least one carbonatom or an aryl group having at least six carbon atoms, and preferablycomprising a C₁ to C₂₀ alkyl group or C₆ to C₂₀ aryl group. Theformation of Grignard reagents, typically by the reaction of an organichalide with magnesium metal in a non-reactive solvent, are well known inthe art. In the preferred embodiment of the invention, the Grignardreagent is prepared using a methyl-tetrahydrofuran solvent, mostpreferably 2-methyl-THF. Examples of Grignard reagents suitable hereininclude a variety of substituted and unsubstituted aryl and alkylGrignard reagents including methyl, ethyl, isopropyl, butyl, sec-butyl,tert-butyl, 2-methoxyphenyl, t-amyl, t-octyl, hexyl, pentyl, and 1-octylmagnesium halides, such as magnesium bromides and magnesium chlorides.Preferred Grignard reagents include tert-butyl magnesium chloride andtert-butyl magnesium bromide. A most preferred Grignard reagent istert-butyl magnesium chloride. The polymerization reaction is preferablycarried out at a reaction temperature of from about −20° C. to about110° C., more preferably from about 0° C. to about 80° C. and mostpreferably from about 65° C. to about 75° C. The reaction is preferablycarried out for about 5 min to about 24 hours.

The reaction of the thiophene monomer with magnesium metal results inthe formation of an intermediate compound which preferably compriseseither the structure:

or the structure:wherein R comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group,a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀ arylgroup, fluorine or NO₂. The bromine and chlorine groups may also besubstituted with other halogen groups, so long as the two are not thesame.

Once this intermediate is formed, it is then reacted with apolymerization catalyst in order to polymerize the thiophene and form aregioregular substituted polythiophene reaction product, particularly apoly(3-substituted) thiophene reaction product. The polymerizationcatalyst preferably comprises a suitable nickel or palladium catalyst.Suitable catalysts non-exclusively include materials selected from thegroup consisting of Ni (II), Ni (0), Pd(II) and Pd(0) compounds. Moreparticularly, [1,3-bis(diphenylphosphino)propane]dichloronickel(II),nickel (II) acetylacetonate, 1,2-bis(diphenylphosphino)ethane nickel(II)chloride, dichlorobis(triphenylphosphine) palladium (II); complexes ofnickel (II) acetylacetonate and tri-tert-butylphosphine,triadamantylphosphine, 1,3-bis(2,4,6-trimethylphenyl)imidazoliumchloride, 1,3-bis(2,6-diisopropylphenyl),1,3-bis(2,6-diisopropylphenyl)imidazolium chloride,1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene,1,3-diadamantyl-imidazolium chloride,1,3-bis(2,4,6-trimethylphenyl)-imidazolidinium chloride,1,3-bis(2,6-diisopropylphenyl)-imidazolidinium chloride and suspensionsand combinations thereof. Catalyst suspensions are preferably suspendedin a Grignard reagent as described in the examples below. In the mostpreferred embodiment of the invention, the catalyst comprises[1,3-bis(diphenylphosphino)propane]nickel (II) chloride,1,2-bis(diphenylphosphino)ethane nickel(II) chloride or a 1:1 complex ofnickel (II) acetylacetonate and1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride.

The catalyst may be added in a second step to a container which containsthe already formed intermediate, or alternately each of the monomer,magnesium metal, Grignard reagent, solvent and catalyst may be combinedin a single step. In the preferred embodiment of the invention, thecatalyst is added after the intermediate is formed. The catalyst may beadded by itself or in combination with a solvent. Preferably, thecatalyst is prepared in the presence of a tetrahydrofuran solvent (e.g.dry THF), more preferably a methyl-tetrahydrofuran solvent, mostpreferably a 2-methyl-THF solvent. In another alternate embodiment, thepolymerization catalyst, may be generated in-situ during the reactionprocess. For example, a Nickel (0) catalyst may be generated in-situthrough the following reaction process:

Said catalyst compound preferably comprises a catalyst concentration offrom about 1% by weight to about 50 mol % by weight, more preferably 5%by weight to about 20% by weight in the solvent. Alternately, thepolymerization catalyst may comprise a combination of a catalystcompound with an organomagnesium Grignard reagent, such as tert-butylmagnesium chloride. In this embodiment, said catalyst compoundpreferably comprises a catalyst concentration of from about 1% by weightto about 20% by weight, more preferably 5% by weight to about 10% byweight in the Grignard reagent.

In the preferred embodiment of the invention, the catalyst is combinedin a catalyst:intermediate monomer mol ratio of from about 0.001 mol %to about 10 mol %, more preferably from about 0.1 to about 1 mol % withthe intermediate. The polymerization reaction is preferably carried outat a reaction temperature of from about 20° C. to about 100° C., morepreferably from about 50° C. to about 90° C. and most preferably fromabout 70° C. to about 80° C. The reaction is preferably carried out forabout 5 min to about 24 hours. It has been found that the temperature ofthe above described reactions are very important to achieving theregioregularity of the polythiophene. A reaction temperature of 80° C.in particular has been found to give a high regioregularity.

In the preferred embodiment of the invention, the crude polythiopheneproduct is further treated by reacting it with from about 1 mol % toabout 20 mol % of a trialkylphosphite compound, more preferably fromabout 5 mol % to about 10 mol %, to further refine the final product.Said trialkylphosphite compound may generally comprise any alkyl grouphaving at least one carbon atom, but preferably comprises a C₁ to aboutC₄ alkyl group, and most preferably comprises triethylphosphite.Further, the crude material is preferably solidified by the addition ofa solvent such as alkanes, acidic acid esters and mixtures thereof at acrude:solvent ratio of about 1:5 to about 1:100. Particularly preferredsolvents include ethylacetate, hexane, heptane, dichloromethane andchloroform. The most preferred solvent is ethylacetate.

The resulting regioregular polythiophene has the following structure:

wherein R comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group,a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀ arylgroup, fluorine or NO₂, and wherein n comprises at least about 2,preferably from about 2 to about 10,000, and more preferably n is fromabout 2 to about 1000 repeating thiophene units. It is within the scopeof the invention that n may comprise even greater than 10,000. Whilethis structure illustrates the R group as being in the 3-position of thethiophene ring, for the purposes of this invention, the structure shouldbe interpreted as having said R group at either the 3-position or the4-position on the thiophene ring. The bond between adjacent repeatingthiophene units is a C—C bond of the thiophene rings, with the2-position of one thiophene ring connecting with the 5-position of anadjacent thiophene ring to form the desired 2,5′ head-to-tailregioregular structure.

As discussed herein, the regioregular poly-(3-substituted) thiophenesformed by the process of the invention have enhanced regioregularity,and hence superior conductivity properties, compared topoly-(3-substituted) thiophenes formed using processes of the relatedart. The regioregular polythiophenes of the invention have been found tohave a regioregularity of greater than about 90%, more preferably about95% and most preferably have a regioregularity of greater than or equalto about 99%. Additionally, the regioregular polythiophenes formed bythe processes of the invention exhibit a higher charge carrier mobility(μ) and on/off ratio (current modulation) than regioregularpolythiophenes formed via processes described in the related art. Thepolymers, films and articles formed from the processes of the inventionhave a preferred mobility of at least about 1×10⁻² cm²/Vs and an on/offratio of at least about 1×10³. However, these charge carrier mobilityand current modulation (on/off ratio) numbers, and those in the examplesbelow, apply to the crude assay of the reaction product and the mobilityand on/off ratio of a final product can be significantly increasedthrough treatment, e.g. extraction or heat treatment, to mobility levelsof 0.05-0.1 cm⁻²/Vs or greater and on/off ratios of 1×10⁵-1×10⁶ orgreater. Additional treatments (e.g. treatment with solvents) may beconducted after extraction to further improve the conductivityproperties of the reaction product.

As described below, for example, in Example 1, a regioregularpolythiophene having 93.5% regioregularity is achieved having highmobility characteristics of at least about 3.6×10⁻² cm²/Vs with a on/offratio of 4×10³. In Example 6, a regioregular polythiophene having 93.3%regioregularity is achieved having high mobility characteristics of atleast about 3.2×10⁻² cm²/Vs with a on/off ratio of 1×10⁵. Such polymersare capable of forming articles and devices with vastly improvedconductivity performance compared to those formed using othertechniques, such as those prepared according to U.S. Pat. No. 6,166,172to McCullough (μ=9.3×10⁻³ cm²/Vs, on/off ratio=1×10⁴) and tocommercially available polythiophenes formed using well known Rieketechniques (μ=1.4×10⁻³ cm²/Vs, on/off ratio=1×10³). The process of theinvention has been found to be particularly desirable for the formationof regioregular poly(3-hexylthiophenes) and regioregularpoly(3-decylthiophenes). Overall, the crude assay of the polythiophenereaction products formed from the processes of the invention haveimproved charge carrier mobility and on/off ratio properties and areformed much more efficiently and economically than any other known priorart process.

The materials of the present invention have been found to be extremelyattractive for use as conductive polymers and films useful in theproduction of conductive articles including electrical and opticaldevices such as organic field-effect transistors or solar cells. Filmsand articles may be formed using techniques that are well known in theart. One well known method for forming a film is extrusion. In a typicalextrusion process, the polymeric material for each individual film layeris fed into infeed hoppers of one or more extruders, each extruderhandling the material for one or more layers. A melted and plasticatedpolymer stream from individual extruders is fed into a single manifoldco-extrusion die. If forming a single layer film, a single layer ofpolymer material will emerge from the die. If forming a multilayer film,multiple layers are juxtaposed while in the die and combined, thenemerge from the die as a single multiple layer film of polymericmaterial. After exiting the die, the film is cast onto a firstcontrolled temperature casting roll, passes around the first roll, andthen onto a second controlled temperature roll, which is normally coolerthan the first roll. The controlled temperature rolls largely controlthe rate of cooling of the film after it exits the die. Additional rollsmay be employed. In another method, the film forming apparatus may beone which is referred to in the art as a blown film apparatus andincludes a multi-manifold circular die head for bubble blown filmthrough which a plasticized film composition is forced and formed into afilm bubble which may ultimately be collapsed and formed into a film.Processes of coextrusion to form film and sheet laminates are generallyknown. Typical coextrusion techniques are described in U.S. Pat. Nos.5,139,878 and 4,677,017. The polythiophene materials may also be formedinto pellets and stored for future use and/or sale.

The following examples serve to illustrate the invention:

EXAMPLE 1

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 75 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for an additional 1.5 h at 70° C. At 60° C. asuspension of Ni(dppe)Cl₂ (93 mg, 0.177 mmol) in 12.5 ml2-methyltetrahydrofurane was added to the reaction mixture over a periodof 30 min and then the mixture was stirred for additional 3 h at 80° C.Triethylphosphite (0.5 g, 3 mmol) was added to the reaction mixture andthe mixture was stirred for additional 30 min at 80° C. Next, tracemetals were removed using conventional distillation and filtrationtechniques. After trace metals were removed, the remaining material wasdissolved in 10 ml toluene and added to 100 ml of ethyl acetate,creating a suspension. The suspension was then stirred for 30 min at 80°C., cooled down and filtered off. The residue was washed two times withethylacetate (2×20 ml) and was dried. The process yielded 4.8 g (81%)poly(3-hexyl)thiophene having a regioregularity of 93.5%. Otherproperties include the following: Mn=10232, Mw=19543, Tm=224° C.,Tmr=188° C., UV (CHCl₃: max=450.79 nm; film: 521, 550, 602 nm), chargecarrier mobility (μ)=3.6×10⁻² cm²/Vs, on/off-ratio=4×10³.

EXAMPLE 2

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 75 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(acac)₂ (45.6 mg, 0.177 mmol),1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (121 mg, 0.355 mmol)and tert-butylmagnesiumchloride solution (0.71 ml, 1 m in THF) in 20 ml2-methyltetrahydrofurane was added to the reaction mixture over a periodof 30 min. The reaction mixture was stirred for additional 3 h at 80° C.Triethylphosphite (0.5 g, 3 mmol) was added to the reaction mixture andthe mixture was stirred for additional 30 min at 80° C. Trace metalswere removed using conventional techniques and a polythiophene productwas separated out. The process yielded 2.68 g (45%)poly(3-hexyl)thiophene having a regioregularity of 91.35%. Otherproperties included: Mn=17523, Mw=55053, Tm=228.66° C., Tmr=187.43° C.,UV (CHCl₃: max=449.98 nm; film: 522, 554, 603 nm); JSC=16.5 mA/cm2,T=350K (15.3 mA/cm2 @ 305K), VOC=550 mV Power Efficiency 3.1% under 1Sun (100 mW/cm2); charge carrier mobility (μ)=3.9×10⁻² cm²/Vs,on/off-ratio=1×10³.

EXAMPLE 3

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 75 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(dppp)Cl₂ (160 mg, 0.355 mmol) andtert-butylmagnesiumchloride solution (1.35 ml, 1 m in THF) in 20 ml2-methyltetrahydrofurane was added to the reaction mixture over a periodof 30 min. The reaction mixture was stirred for additional 3 h at 80° C.Triethylphosphite (0.5 g, 3 mmol) was added to the reaction mixture andthe reaction mixture was stirred for additional 30 min at 80° C. Tracemetals were removed using conventional techniques and a polythiopheneproduct was separated out. The process yielded 3.28 g (55%)poly(3-hexyl)thiophene having a regioregularity of 91%. Other propertiesincluded: Mn=10596, Mw=18303, UV (CHCl₃: max=448 nm; film: 523, 553, 606nm), charge carrier mobility (μ)=3.2×10⁻² cm²/Vs, on/off-ratio=1×10⁴.

EXAMPLE 4

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 50 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(acac)₂ (91 mg, 0.355 mmol),1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (125.1 mg, 0.355mmol) and tert-butylmagnesiumchloride solution (3.54 ml, 1 m in THF) in20 ml 2-methyltetrahydrofurane was added to the reaction mixture over aperiod of 30 min. The reaction mixture was stirred for additional 3 h at80° C. Triethylphosphite (0.5 g, 3 mmol) was added to the reactionmixture and the mixture was stirred for additional 30 min at 80° C.Trace metals were removed using conventional techniques and apolythiophene product was separated out. The process yielded 3.3 g (56%)poly(3-hexyl)thiophene having a regioregularity of 91.14%. Otherproperties included: Mn=23768, Mw=56963, Tm=299.8° C., Tmr=190.69° C.,UV (CHCl₃: max=451.82 nm; film: 524, 556, 605 nm), charge carriermobility (μ)=2.2×10⁻² cm²/Vs, on/off-ratio=3×10³.

EXAMPLE 5

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 50 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(dppe)Cl₂ (186 mg, 0.355 mmol) andtert-butylmagnesiumchloride solution (6 ml, 1 m in THF) in 25 ml2-methyltetrahydrofurane was added to the reaction mixture over a periodof 30 min. The reaction mixture was stirred for additional 3 h at 80° C.Triethylphosphite (0.5 g, 3 mmol) was added to the reaction mixture andthe mixture was stirred for additional 30 min at 80° C. Trace metalswere removed using conventional techniques and a polythiophene productwas separated out. The process yielded 3.8 g (64%)poly(3-hexyl)thiophene having a regioregularity of 92.58%. Otherproperties included: Mn=10100, Mw=24500, Tm=220.5° C., Tmr=183.64° C.,UV (CHCl₃: max=447.86 nm; film: 516, 553, 606 nm), charge carriermobility (μ)=1.8×10⁻² cm² Vs, on/off-ratio=3×10⁵.

EXAMPLE 6

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 50 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(acac)₂ (91 mg, 0.355 mmol),1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride (125.1 mg, 0.355mmol) and tert-butylmagnesiumchloride solution (4 ml, 1 m in THF) in 20ml 2-methyltetrahydrofurane was added to the reaction mixture over aperiod of 30 min. The reaction mixture was stirred for additional 3 h at80° C. Triethylphosphite (0.5 g, 3 mmol) was added to the reactionmixture and the mixture was stirred for additional 30 min at 80° C.Trace metals were removed using conventional techniques and apolythiophene product was separated out. The process yielded 1.5 g (25%)poly(3-hexyl)thiophene having a regioregularity of 93.3%. Otherproperties included: Mn=16861, Mw=33147, Tm=225.5° C., Tmr=195.5° C., UV(CHCl₃: max=450.98 nm; film: 551 nm), charge carrier mobility(μ)=3.2×10⁻² cm²/Vs, on/off-ratio=1×10⁵.

EXAMPLE 7

5-Bromo-2-chloro-3-hexylthiophene (10 g, 0.0355 mol) was added over aperiod of 30 min to a mixture of 50 ml 2-methyltetrahydrofurane,magnesium (0.86 g, 0.0355 mol) and 0.15 ml of a 1 molar solution oftert-butylmagnesiumchloride solution in THF at a temperature of 60-70°C. The mixture was stirred for additional 1.5 h at 70° C. At 60° C. asuspension of Ni(dppp)Cl₂ (190 mg, 0.177 mmol) in 20 ml2-methyltetrahydrofurane was added to the reaction mixture over a periodof 30 min. The reaction mixture was stirred for additional 3 h at 80° C.Trace metals were removed using conventional techniques and apolythiophene product was separated out. The process yielded 4.4 g (75%)poly(3-hexyl)thiophene having a regioregularity of 90%. Other propertiesincluded: Mn=7837, Mw=15283, UV (CHCl₃: max=448.11 nm; film: 520, 550,607 nm).

While the present invention has been particularly shown and describedwith reference to preferred embodiments, it will be readily appreciatedby those of ordinary skill in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe invention. It is intended that the claims be interpreted to coverthe disclosed embodiment, those alternatives which have been discussedabove and all equivalents thereto.

1. A method of forming a substituted polythiophene, comprising: a)providing a solvent soluble, substituted thiophene monomer, wherein saidmonomer has the structure:

wherein X₁ and X₂ are different and each comprises a halogen atom, withat least one of the halogen atoms being capable of bonding withmagnesium; R₁ comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀aryl group, fluorine or NO₂; R₂ comprises hydrogen, fluorine, NO₂ or aC₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group, a C₁ to C₂₀ O-alkylgroup, a C₁ to C₂₀ S-alkyl group or a C₆ to C₂₀ aryl group; b) combiningthe substituted thiophene monomer with magnesium and a solvent to form aregiochemical intermediate; and c) reacting the regiochemicalintermediate with a polymerization catalyst under conditions sufficientto polymerize the intermediate producing a regioregular, substitutedpolythiophene reaction product having repeating units of the structure:

wherein R comprises either a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ toC₂₀ aryl group, fluorine or NO₂; the polymer having a charge carriermobility (μ) of at least about 1×10⁻² cm²/Vs and an on/off ratio of atleast about 1×10³, and wherein n comprises from about 2 to about 10,000.2. The method of claim 1 wherein R₁ comprises a C₁ to C₂₀ alkyl group.3. The method of claim 1 wherein R₁ comprises an C₁ to C₂₀ O-alkylgroup.
 4. The method of claim 1 wherein R₁ comprises an C₁ to C₂₀S-alkyl group.
 5. The method of claim 1 wherein R₁ comprises a C₆ to C₂₀aryl group.
 6. The method of claim 1 wherein R₂ comprises hydrogen. 7.The method of claim 1 wherein the substituted thiophene monomercomprises either 2-bromo-5-chloro-3-hexylthiophene or5-bromo-2-chloro-3-hexylthiophene.
 8. The method of claim 1 wherein saidsolvent comprises methyl-tetrahydrofuran.
 9. The method of claim 1wherein an equimolar amount of said magnesium metal is reacted with saidsubstituted thiophene monomer.
 10. The method of claim 1 wherein step b)further comprises combining said substituted thiophene monomer,magnesium metal and solvent with an organomagnesium Grignard reagent.11. The method of claim 10 wherein a catalytic amount of from about 0.1%to about 10 mol % of said organomagnesium Grignard reagent is used. 12.The method of claim 10 wherein said organomagnesium Grignard reagentcomprises tert-butyl magnesium chloride.
 13. The method of claim 1wherein said polymerization catalyst comprises a material selected fromthe group consisting of Ni (II), Ni (0), Pd(II) and Pd(0) compounds. 14.The method of claim 1 wherein said polymerization catalyst is selectedfrom the group consisting of[1,3-bis(diphenylphosphino)propane]dichloronickel(II), nickel (II)acetylacetonate, 1,2-bis(diphenylphosphino)ethane nickel(II) chloride,dichlorobis(triphenylphosphine) palladium (II); complexes of nickel (II)acetylacetonate and tri-tert-butylphosphine, triadamantylphosphine,1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride,1,3-bis(2,6-diisopropylphenyl),1,3-bis(2,6-diisopropylphenyl)imidazolium chloride,1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene,1,3-diadamantyl-imidazolium chloride,1,3-bis(2,4,6-trimethylphenyl)-imidazolidinium chloride,1,3-bis(2,6-diisopropylphenyl)-imidazolidinium chloride and suspensionsand combinations thereof.
 15. The method of claim 1 wherein saidpolymerization catalyst comprises a combination of a catalyst compoundwith an organomagnesium Grignard reagent.
 16. The method of claim 1wherein said polymerization catalyst comprises[1,3-bis(diphenylphosphino)propane]nickel (II) chloride.
 17. The methodof claim 1 wherein said polymerization catalyst comprises1,2-bis(diphenylphosphino)ethane nickel(II) chloride.
 18. The method ofclaim 1 wherein said polymerization catalyst comprises a complex ofnickel (II) acetylacetonate and1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride.
 19. The method ofclaim 1 which further comprises reacting said substituted polythiophenereaction product with a trialkylphosphite compound.
 20. The method ofclaim 1 wherein the substituted polythiophene reaction product has aregioregularity of at least about 90%, a charge carrier mobility (μ) ofat least about 1×10⁻² cm²/Vs and an on/off ratio of at least about1×10³.
 21. A compound having the structure:

wherein R comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group,a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group, a C₆ to C₂₀ arylgroup, fluorine or NO₂, and wherein n comprises from about 2 to about10,000.
 22. A compound having the structure:

R comprises either a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group, aC₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ to C₂₀ arylgroup, fluorine or NO₂.
 23. A regioregular polythiophene polymer havingrepeating units of the structure:

wherein R comprises either a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ toC₂₀ aryl group, fluorine or NO₂; the polymer having a charge carriermobility (μ) of at least about 1×10⁻² cm²/Vs and an on/off ratio of atleast about 1×10³, and wherein n comprises from about 2 to about 10,000.24. The regioregular polymer of claim 23 which comprises apoly(3-hexylthiophene).
 25. The regioregular polymer of claim 23 whichcomprises a poly(3-decylthiophene).
 26. A film formed from aregioregular, substituted polythiophene, which film is formed by: I.forming a regioregular, substituted polythiophene by: a) providing asolvent soluble, substituted thiophene monomer, wherein said monomer hasthe structure:

wherein X₁ and X₂ are different and each comprises a halogen atom, withat least one of the halogen atoms being capable of bonding withmagnesium; R₁ comprises a C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkylgroup, a C₁ to C₂₀ O-alkyl group, a C₁ to C₂₀ S-alkyl group or a C₆ toC₂₀ aryl group, fluorine or NO₂; R₂ comprises hydrogen, fluorine, NO₂ ora C₁ to C₂₀ alkyl group, a C₁ to C₂₀ F-alkyl group, a C₁ to C₂₀ O-alkylgroup, a C₁ to C₂₀ S-alkyl group or a C₆ to C₂₀ aryl group; b) combiningthe substituted thiophene monomer with magnesium and a solvent to form aregiochemical intermediate; and c) reacting the regiochemicalintermediate with a polymerization catalyst under conditions sufficientto polymerize the intermediate producing a substituted polythiophenereaction product; the polythiophene having a regioregularity of at leastabout 90%, a charge carrier mobility (μ) of at least about 1×10⁻² cm²/Vsand an on/off ratio of at least about 1×10³; and II. forming theregioregular, substituted polythiophene of (I) into a film.
 27. Anarticle formed from the film of claim 26.